Motor control.



PATENTED JUNE 16, 1908.

F. EIGHBERG.

MOTOR CONTROL.

APPLICATION FILED JAN.23,1907.

WIT/M55555. MNTUJ E:

3 THEDHIC EIC'JIB HG.

ATT'YT wit regulation has been the motor.

UNITED STATES PATENT OFFICE.

' FRIEDRICH EICHBERG, OF BERLIN, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YORK.

MOTOR CONTROL.

Specification of Letters Batent.

PatentedJune 16, 1908.

' Application filed January 23, 1907. Serial No. 353,648.

' To all whom it may concern Be it known that I, FRIEDRICH EioriBERe,

a subj cot of the Emperor of Austria-Hungary,

residing at Berlin, Germany, have invented fication.

My'inVention relates to alternating-current motor control systems, andparticularly. to

control systems for railway motors provideda with regulating, transformers; and itsv object is to provide a'n'ovel arrangement of the controlling switches possessing certain advantages not hereto'forejobtained. It has been pro o sedheretofore to provide such systems two .transformers,one connected on. its primary side to the source of current, and the other connected on its secondary side to the motor; the secondary side of the first transformer being connected to the primary side. ofthe second. When'such transformers have been arranged heretofore with-means for'varying the ratio of transformation to regulate the motor speed and torque, the obtained-by means of switches connected to the secondary sides of the transformers.

My invention consists in comiecting the switches tothe secondary side of the transformer connected to the source and to the primary side of the transformer connected to By this arrangement I am enabled to obtain with single-pole switchesa double break in the circuit containing the switches. Moreover, the switches may be so arranged that the difference in voltage atthe several switches is not great, so that the switches may be mounted close together, or even in a single casing. Furthermore,- since all of the switches are in the same circuit and handle currents of the same amount and v'olta 2;, they can all be exactly alike in design.

ile not limited in its broader aspect to any one type of motor, my invention is particularly apfplicable to a type of motor described in Winter and myself, comprisin an inducing the line of magnetization of the inducing winding, and 'a second set of brushes disiplaced ninety electrical degrees from the rst set and carrying the magnetizin current of the motor, To obtain a series aracteristic in s'ii'cha motor, and to regulate .its

applicable to anynumber 0f ormer applications filed by G.

speed and torque, a transformer may be provided in series.- with the indiicing winding with its secondary connected to the second set of brushes. By varying. the ratio of transformation of the transformer the motor so may be regulated as to speed and torque. The transformers that have,been provided heretofore for this purpose have been arranged tohave the number of secondary turns varied, but by my present invention 1 e5 arrange the transformer to have itsprimary turns varied in number. When used in combinationwitha transformer inserted between the source and the motor, I am enabled to obtain. the advantages which have been above mentioned.

.l y invention will best be understood by reference to the accompanying drawings, in which Figure 1 shows! diagrammatically a motorcontrol system arranged in accordance with my. invention, and Fig. 2 shows a modification of the same. I

In the drawings A represents the motor.

I have shown only a single motor, but it will so be understood that my invention is equally motors con nected either in series-or in parallelfv I a represents the inducing winding of the motor, and a th'earmature or rotor winding,

which is provided with commutator brushes 6 b short-circuiting the armature winding on the line of magnetization of the inducing winding. b I) represent a second set of brushes displaced ninety electrical degrees from'the first set. B represents a transformer or auto-transformer connected in series with the inducing winding a. The secondary leads of the transformer are connected to the brushes 6 b'to supply the magnetizing current to the motor through these rushes. transformer B is provided with a number of primary leads,

as shown. C represents a second transformer, which is connected on Its. rimary 10 Side to the source of current indicate by the trolley D. The secondary is provided with winding,:a rotor windin provi ed with commutator and brushes s ort-circuiting it on a lurality of leads, as shown.

n Fig. 1 I have shown the transformer B as an auto-transformer, and thetransformer This 1 is ordinarily preferable, where the primary and secondary voltages differ largely, to use a transformer with two windings, while, if the primary and secondary voltages do not greatly differ, an auto-transformer is cheaper and therefore preferable. E to represent magnetically-actuated switches connected to the secondary leads of the transformer C, and to the primary leads of the transformer B, and arranged to connect each transformer to different points on the other. In other words, these switches act to connect the two transformers to each other and to vary the effective number of secozfidary turns of transformer C, and the effec'ive number of pri mary turns of transformer B. F represents the master switch, provided with contactfingersf to f controlling the magnetically actuated switches or contactors E to E.

The actuating windings of these contactors are supplied from any suitable source of current. I have shown them in Fig. 1 connected in a circuit including a small portion of the primary winding of transformer C.

The circuit connections in. the different positions of the master controlling switch F may be'traced as follows: When thisswitch is moved to its first running position, as indicated by the first dotted line, a circuit is closed from a point on transformer C through .fingers f and f to contactor winding E,

thence through contactor E to ground. contactors E and E consequently pick up their armatures connecting the inner secondis maximum, so that it starts with high torque. In the second positionof switch F, contactor E is denergized, and contactor E is energized thereby including a greater number of secondary turns of transformer C in circuit, and increasing the voltage im pressed upon the motor and transformer B in series. In the third position of the switch, contactor FF is dencrgized and contactor E is energizetl, thereby impressing the'full secondary voltage of transformer C on the motor and transformer B. In its fourth position, contactor E isjdeen ergized, and contactor E is energized, thereby reducing the effective primaryturns of transformer B, and consequently reducing the secondary current of the transformer and the cross-magnetization of the motor, allowing the motor to speed up.

' same potential.

In other words, the cross-magnetization of the motor In the fifth position of switch F contactor E .is denergized, and contactor E is energized,

is returned to its off-position, the circuit from the secondary'sideof transformer'O to the primary side oftranformer B is openedin. two places, and this result 115 obtained with single-pole switch contacts.- In this figure all the contactors are-placed on the same side of the circuit; the other side of the circuit,

extending from the upper secondary terminal of transformer C to the right-hand terminal of the inducing winding a, containing no switches. The advantage of placing the contactors all in the same side of the circuit, as shown in. Fig. 1, is that they can all be con nected together, as shown in this figure, so that the movable contacts of all the contactors may be at exactly the same potential,

while the stationary contacts are nearly the There is consequently little danger of a short-circuit between different contactors, so that they may all be placed in a single casing, if desired.

On the other hand, if the contactors are divided between the two sides of the circuit, the circuit is" still broken in two places,and the motor is totally disconnected from the transformer C when the controlling switch is in off position. This modification is shown in 1* ig. 2. The circuit connections established by the contactors are. similar, to those established in Fig. 1, and require no detailed ex lanation. contactors to E are in oneside of the circuit, while contactors E to E are in the other side, so that when switch F is in its off-position, as shown, both sides ofthe cir- It will be noted that cuit are open and the motor is wholly disconnected from transformer C. In this figure, transformer C is shown as an auto- ..transformer, instead of as a two-winding transformer, as in Fig 1. As has been explained, this difierence is immaterial, and

the choice between the two forms is determined by the particular conditions of each case.

ing connected to the source, a second transformer having its secondary winding con nected to-the motor, and means for connecting the other .two windings of the two transformers to different points on each other.

2. In combination with an alternatingcurrent motor and a source of current therefor, a transformer connected on its primary side to the source and having more t tan two secondary leads, a second transformer connected on its secondary side to the motor and having more than two primary leads,

and switch contacts for connecting together in different combinations the secondary leads of the first transformer and the primary leads of the second transformer.

23. In combination with an alternatingcurrent motor and a source of current there for, a transformer connected to the source, a second transformer connected to the motor, connections between said transformers, and switch contacts arranged to vary the effective number of secondary turns of the first transformer and the effective number of primary turns of the second transformer.

4. In combination with an alternatingcurrent motor and a source of current therefor, a transformer having its primary winding connected. to the source, a second transformer having its secondary winding connected to the motor, and magnetically-,

actuated switches arranged to connect the other two windings of the two transformers to different points on each other.

5. In combination with an alternatingcurrent motor and a source of current therefor, a transformer connected on its Jrimary side to the source and having more t ian two secondary leads, a second transformer connected on its. secondary side to the motor and having more than two primary leads, and magnetically -actuated switches arranged to connect together in different combinations the secondary leads of the first transformer and the primary leads, of the second transformer.

6. The combination with an alternatingcurrent motor, comprising an-inducing winding, a rotor winding provided with commutator and brushes short-circuiting it on the line of magnetization of the inducing winding, and a second set of brushes displaced ninety electrical dcgrefs from the iirst set, of a transformer comm-cud in series with the inducing winding, secondary leads from said transformer to the second set of brushes, and means for varying the infective number of primary turns of said transformer.

7. The combination with an alternatingcurrent motorcomprising an inducing wind-- mutator and brushes s iort-circuiting it on the line ofmagnetization of the inducing winding, and a second set of brushes dis-- placed ninety electrical degrees from the first set, of a transformer connected in series with the inducing winding, secondary leads from said transformer to the second set of brushes, means for varying the effective number of primary turns of saidtransformer, a source of current for the motor, a second transformer connected on its primaryside to the source and on its secondary side to the motor and first transformer, and means for varying the effective number of secondary turns of the second transformer.

In witness whereof, I have hereunto set my hand this 8th day of- January, 1907.

FRIEDRICH EIQHB'ERGL Witnesses EMANUEL ROSENBERG, MAXIMILIAN FINNER.

111g, a rotor winding provided with com- 

